Crank-case ventilation



Filed May 29, 1926 3111x2144 at Patented May 14,1929.

UNITED STATES PATENT OFFICE.

WALTER S. COCHRANE, OF FLINT, MICHIGAN, ASSIGNOR TO GENERAL MOTORS COR- PORATION, OF DETROIT, MICHIGAN, A CORPORATION OF DELAWARE.

CRANK-CASE VENTILATION.

Application filed May 29,

This invention relates to crankcase ventilation.

It is the object of the invention to remove from the crankcase the gases which escape past the pistons and ordinarily condense and mingle with the lubricating oil seriously reducing its lubricating qualities. This is accompllshed by circulating air through the crankcase, the air stream not only removing leakage gases, but also effecting gasification or evaporation of va ors which have previously condensed and mingled with the oil. For this purpose the crankcase is provided with an air admission opening and with an opening to which suction is applied to withdraw the mixed air and vapors.

I have preferred to employ as a source of suction the aspirating action of a portion of the air stream supplied by the usual cooling fan, and to accentuate such action have employed a funnel-shaped conduit to gather the air currents and direct them across or in proximity to the suction opening so that the gases from the crankcase are entrained with the stream and carried away.

To prevent loss of oil from the crankcase I have preferably so designed my suction conduit that separation of particles of oil is effected prior to discharge of the air stream from the engine. I have also preferred to employ the Venturi principle in the design of my suction conduit in order to accentuate the aspirating action. To dispose of the gases with the least annoyance to the occupants of the car I have carried them to a point below the motor and have preferably so shaped the conduit at its discharge end that an aspirating effect is produced thereon by the air currents set up by the motion of the car, this further assisting in the removal of vapors. I have preferred to combine my ventilating device with the usual oil filling tube now provided upon automobile engines, and for the air admission opening have made use of the usual crankcase breather. However, if desired my ventilating system may be employed independently of these parts.

Figure 1 is a side elevation of a conventional automobile engine showing my improved crankcase ventilating system applied thereto.

Figure 2 is a front elevation of the structure shown in Figure 1, the parts being shown in section.

The reference character 2 indicates a con- 1926. Serial no. 112,625.

ventional type of internal combustion engine, the engine being provided with the usual cooling fan 4 and crankcase 6 serving as a lubricant'reservoir. In the operation of the engine this lubricant becomes diluted by vunburnt fuel, water vapor and other gases which escape past the pistons and condense in the crankcase.

To remedy this dilution I have arranged for the circulation of air through the crankcase. While provision may be made for the admission of air at a number of different points, I have preferred to make use of the breather tube 8 customarily provided.

Upon this breather tube is mounted a cap 10 having a depending flange 12. As the breather tube is arranged in the path of the air currents from the fan 6, the cap 10 serves to prevent the entrance of dust particles into the breather, these particles because of their greater inertia, being carried beyond the entrance opening.

' While the cap 10 may be supported in any desired manner, I prefer to make use of clamp 14 having upwardly extending diverging arms 16 secured to the flange 12.

The air entering the crankcase through the breather is discharged through the opening 18 at the forward end of the motor through the operation of a suction or aspirating device, a description of which follows.

In the opening 18 is secured a fitting 20 in the form of a tubular member 22 having a partition 24: therein dividing it into an outlet passage 26 and a discharge passage 28, the partition stopping short of the top of the tubular member 22 to establish communication between these passages.

The upper end of the member 22 is open and is closed by removable cap 29, this arrangement permitting the passage 26 to serve as an oil filling opening.

The lower end of the discharge passage 28 communicates with the open ended conduit 30 having a constriction 32 therein forming a venturi. To one end of this conduit is se cured funnel member 34 having its large end arranged at the rear of the fan 4. The small end of the funnel 34 preferably extends with in the conduit 30 to within a short distance of the constricted portion as shown. In the other end of the conduit 30 is secured tube 36, the free end of which is preferably carried downwardly through aperture 38 in the customary drip pan. The lower end of the tube 36 is sheared at an angle as indicated at 40.

The device operates as follows:

The funnel 34 gathers air currents from the rear of the fan and delivers them into the Venturi portion of the conduit 30, where they produce an aspirating effect upon the gases in passages 26 and 28 entraining the gases and discharging them through tube 36 beneath the engine.

The gases thus withdrawn from the crankcase are replaced by air, cleaned as previously described, entering the crankcase through the breather 8.

The provision .of a rearwardly facing angled end on the conduit 36 causes the air currents resulting from the motion of the car to produce a slight aspirating effect on the tube, this action assisting the main aspirating action resulting from the flow of air currents through the funnel and conduit.

The fact that the gases leaving the crankcase must turn at a sharp angle in travelling from passage 26 into passage 28 results in separation of oil particles from the gases by inertia action. To enhance this action I may provide the partition 24 with a lip 50 which will serve to catch particles of oil and direct them back into the crankcase.

By discharging the air and gases below the drip pan, I avoid any possibility of the fumes entering the car body.

It will be found desirable in practice to provide a bracing means for the upper end of the fitting 20, but for simplicity this feature has been omitted from the drawing.

WVith the above construction a considerable volume of air is passed through the crankcase, and in practice this has been sufiicient to overcome the ill effects produced by leakage gases even when operating under severe winter conditions.

I claim 1. The combination of an automobile engine having a crankcase, means for admitting air to the crankcase, said crankcase being provided with an oil filler tube, a closure for the upper end of said tube, a passage communicating with said tube between its ends and an open-ended conduit communicating with said passage and adapted to convey a stream of air under pressure to exert an aspirating action on said conduit to withdraw vapors from the crankcase.

2. The combination as defined in claim 1,

with a funnel at the rear of said fan for receiving air under pressure therefrom.

3. A fitting for a crankcase opening comprising a tubular member adapted to fit in said opening, a partition in said tubular member dividing the member into an outlet passage and a discharge passage communicating with the outlet passage, and an openended conduit arranged transversely of the axis of said tubular member and communicating with said discharge passage.

4. In combination with the fitting as de-.

scribed in claim 3, a funnel member secured in one end of said open-end conduit.

5. The combination of an en ine having a crankcase provided with an oil her opening, a tube leading from said opening, a partition in the tube dividing it into a main passage communicating with the opening, and an auxiliary passage communicating with the main passage above the partition, a closure for the upper end of the tube, means for applying suction to said auxiliary passage for removing crankcase vapors therefrom, said partition serving to direct into the crankcase oil introduced into said tube and serving to intercept oil particles from the stream of air passing out through the said auxiliary pas-' sage.

6. The combination of an en ine having a crankcase provided with an oil ller opening, a tube leading from said opening, a partition in the tube dividing it into a main passage communicating with the opening, and an auxiliary passage communicating with the main passage above the partition, a closure for the upper end of the tube, a conduit communicating with said auxiliary passage, and means for passing a stream of airthrough said conduit to exert an aspirating action on said auxiliary passage for removing vapors from the crankcase, said partition serving to direct into the crankcase oil introduced through said tube and to intercept particles of oil carried by said vapors.

7. In the combination as defined in claim 6, said engine being provided with a drip pan and said conduit having a discharge portion extending below said drip pan.

8. In the combination as defined in claim 7 said conduit being provided with a venturi adjacent the point of connection with said passage to increase the suction applied to the crankcase.

In testimony whereof I affix my signature.

WALTER S. COCHRANE. 

